Hi there! Thanks for asking.
You need to use the punctuation mark " Hyphen" in order to separate numbers (regarding to spelling). For example: Twenty-two, Thirty-five, Fifty-one and so on.
Also, you need to use Hyphen when you are going to justify text , Prefixes ( Ex-president, ex.girlfriend) compound words or joining modifiers ( ice-cream-flavored candy or she is a twenty-year-old lady) and some other uses.
One more thing:Be careful and do not get confused with Dash. That's a very similar punctuation mark